> I think the default settings for the AC97 mixer might differ.
> Try mixerctl on the device to get all possible settings.

Thanks.  Way different...

PR'ed driver under 1.4.1:

outputs.master=184,184 volume
inputs.dac=184,184 volume
inputs.video=184,184 volume
inputs.cd=184,184 volume
inputs.line=184,184 volume
inputs.aux=184,184 volume
inputs.mic=248 volume
inputs.mic.preamp=off  [ off on ]
record.source=line  { mic cd line video aux dac }
outputs.select=mic,cd,line,video,aux,dac  { mic cd line video aux dac }

New ac97 driver under -current:

outputs.master=255,255 volume
outputs.master.mute=off  [ off on ]
outputs.mono=255 volume
outputs.mono.mute=on  [ off on ]
outputs.mono.source=mixerout  [ mixerout mic ]
outputs.headphones=255,255 volume
outputs.headphones.mute=off  [ off on ]
outputs.tone=255,255 volume
inputs.speaker=255 volume
inputs.speaker.mute=on  [ off on ]
inputs.phone=191 volume
inputs.phone.mute=on  [ off on ]
inputs.mic=191 volume
inputs.mic.mute=on  [ off on ]
inputs.mic.preamp=off  [ off on ]
inputs.mic.source=mic0  [ mic0 mic1 ]
inputs.line=191,191 volume
inputs.line.mute=on  [ off on ]
inputs.cd=191,191 volume
inputs.cd.mute=on  [ off on ]
inputs.video=191,191 volume
inputs.video.mute=on  [ off on ]
inputs.aux=191,191 volume
inputs.aux.mute=on  [ off on ]
inputs.dac=191,191 volume
inputs.dac.mute=off  [ off on ]
record.source=mic  [ mic cd video aux line mixerout mixeroutmono phone ]
record.volume=255,255 volume
record.volume.mute=off  [ off on ]
record.mic=0 volume
record.mic.mute=off  [ off on ]
outputs.loudness=off  [ off on ]
outputs.spatial=off  [ off on ]
outputs.spatial.center=0 volume
outputs.spatial.depth=0 volume

So a playthrough setting for line-in would be:
mixerctl -w inputs.line.mute=off

And for recording from the line-in would be:
mixerctl -w record.source=line

Is that right?

-allen